Bending machine



F. K. KlRscH BENDING MACHINE Filed June 25, 1942 4 Sheets-Sheet l INVENTOR 4 Sheets-Sheet 2 F. K. KIRSCH BENDING' MACHINE Filed June 25, 1942 May 14 1946.

May 14, 1946. F. K. KlRscH v 2,400,151

BENDING MACHINE Filed June 25, 1942 4 Sheets-Sheet 5 INVENTOR Han/ xzrsc.

May 14, 1946.

F. K. KlRscH v BENDING MACHINE Filed June 25, 1942 4 Sheets-Sheet 4 Swing A TTORNE Y Patented May 14, 1946 BENDING MACHINE Frank K. Kirsch, Detroit, Mich., assigner to Briggs Manufacturingompany, Detroit, Mich., a cor poration .o f Michigan Application .rune 25, 1942, serial No. 448,335

This invention relates to the bending of metal and particularly lengths or strips of metalV of various cross-sectional shapes or congiurations, such as angles, channels, T sections, Z sections, as Well as llat metal strips which are to be bent in the plane of the strips. The invention is especially applicable to the bending of any metal shapes Where the metal strip or other `piece is to be bent angularly, such as Afrom a straight Aform to a .curvediornr and where ordinarily compres.- sive stresses .are set up in the member during the bending operation which tend to produce wrinkles, puckersor .the like.

An-objectof the invention is to provide an improved machine for bending rrietallic members lor sections of various crossfsectional shapes or configurations and in `which fthe metal is subjected to a stretching action in such way as to elimi nate the introduction of compressive stresses in the metal 4fibers and the formation of wrinkles, folds, 4puckersor the 1ike, and also to eliminate or reduce materially any tendency of the metal to recoil or spring back thereby not retaining its desired bent shape and not taking the permanent set which is desired.

A further object .of the invention is to provide a .machine for bending rmetal strips or the like wherein a vforming member is moved in ,a curvilinear path with respect to the strip to be bent which in turn is moved by a `carrier in a path tangential with respect `to the path of travel -of the forming member, the strip being gripped at oppQSte ends by the forming member and the carrier and therate of travelof the forming meinber being greater than that of the `carrier thus causing thestrip to be'bent on the forming member and also stretched .in its length in such manner as to avoid lcompressive stresses resulting in the accumulation of metal lalong the inneredge of the bent strip.

A' ,further object of the invention is to provide ameans for `bending a metal strip, espeallyone that is irregular in cross-section, which tonsists in gripping one end portion of the strip in a forming member and Ycausing the forming ,member rtomove inan .angular path to yvraptlie strip thereon while the opposite end portion .of the Strip .is retained .and caused to travel toward `the forming member at a different rate of speed than that of theforming member.

Another object Yof the invention is to provide a `bending machine for metal strips or the like comprising a forming or bending ,member ,and a carrier member, .each adapted to be attachent@ the metal strip, and'in which these members are fed or caused to travel angularly with respect to eachother and ,at h.differential speeds whereby the strip isbent upon the forming member under tension with the elimination of any wrinkle or fold formations.

Still a further object vof .the invention is to bend a metal strip, such as .one that is angular or irregular in cross-section, into a curved shape and in performing this operation to stre-tch the in etal strip progressively along the .Outer yedge DOition of the strip thereby proijlucing a smoothly bent strip free from Wrinkles along the inner edge ,portion thereof.

Another object yof the invention is to provide a machine for accomplishing the foregoing .comprising two slides ,adapted tobe clamped to opposite ends Yof the work piece or metal strip .and shiitable along angularly related paths one tangential to the other and wherein' means is .previded -for moving one slide at a .different 4.rate of speed than )the other slide.

Another object of the invention is to provide a machine for bending a `metal .strip on `a curve in agivenplane .while at the same vtime stretching orelongating portions .of the strip .to avoid wrinkles or folds during the vbending operation and wherein the 4cons truction Aof themachine .is such as ,to ,permit V'shapingof the strip .dur-ing vthe bending operation. l

A Ifurther object of the invention .is .to provide a metal 4strip .bending and :stretching mechanism Of the foregoing type .which is relatively simple and compact in construction, eiiicient in operaM tion, durable and relatively .easy to operate.

Qther objects Aof this invention .will appear .in the following description and .appended claims, reference being .had to the accompanying ,dra\vings forming `a part Vof this `speciiication wherein like referencecharac-ters designate corresponding parts in .thewseveral views.

Fig. Y1 is a front elevation, partly broken .away of a machine embodying the present ,invention and adapted to carry out ,the herein Vdescribed method.

Fig. Zisan enlarged fragmentary plan View of a portionof the bending mechanism.

`Fig. 3 is la plan view of .themachine .illustrated in Fig. 1`. l

Fig. 4 is van" enlarged section taken substantially .through lines 4-.4of Eig. 3 looking in the directionof thearrows, `parts not on the section line being shown in elevation.

Figs 5 ,ando `are views, respectively, of a metal stripV before andafterit .has beenbent.

Fig. 'I is an enlarged section taken substantially through lines 'I-'I of Fig. 6 looking in the direction of the arrows.

Fig. 8 is a fragmentary view showing diagrammatically the manner in which the bending and stretching action takes place.

Fig. 9 is an enlarged fragmentary elevation showing the clamping or gripping devices adapted to be secured to opposite ends of the strip preparatory to the bending operation.

Fig. l is an enlarged section taken substantially through lines Ill-I 0 of Fig. 2 looking in the direction of the arrows, this View illustrating the device for clamping the front or leading end of the strip.

Fig. 11 is an enlarged section taken substan-A tially through lines Il-H of Fig` 2 looking in the direction of the arrows, this view illustrating the device for clamping the rear or tail end of the strip.

Fig. 12 is an enlarged section taken substantially through lines l2-I2 of Fig, 2 looking in the direction of the arrows.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of be ing practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawings, wherein I have illustrated, by way of example, one embodiment of the present invention, the machine therein shown comprises in general two main slides movable in predetermined angularly related paths for the purpose of bending a metallic strip to the desired shape while stretching the metal so as to eliminate any folds, wrinkles or the like which are likely to be formed on account of the setting up of compressive strains at certain localities of the strip. In the present machine a metal strip C of general T-shape in cross-section is bent into a curved shape and this bending takes place in the plane of the central web of the strip, see Figs. to 7 inclusive. The machine comprises what may be termed a work piece carrying slide A which is adapted to clamp the tail end of the work piece, and also what may be termed a forming slide B which is adapted to clamp the forward or lead ing end of the metal strip. The work piece carrying slide is of duplex construction so that it may be shifted transversely to clamp the work piece against the forming slide at the tangential point of engagement of the two slides. Mechanism is provided for shifting the work piece carrying slide in a rectilinear path tangential to the curvilinear path of travel which is imparted by suitable mechanism to the forming slide. The mechanism for shifting the two slides is controlled through both a speed reducing means as well as a Variable speed mechanism whereby the forming slide is adapted to travel in its curvilinear path at a greater rate of speed than the speed of travel of the work piece carrying slide. As a consequence, as the two slides move forwardly together, one tangentially with respect to the other, the metal strip is in effect wrapped upon the curved forming slide, and due to the differential speed between the two slides the metal strip will be stretched progressively. The amount of stretching is not uniform across the width of the strip, the greatest amount of stretching or elongation taking place along the outer edge of the curved strip and the least amount of stretching occurring along the inner edge of the curved strip, this being illustrated in Fig. 8.

The present machine comprises a suitable table or bed 20 supported above the oor by means of legs 2|. The work piece carrying slide A in the present instance comprises two slide members or plates 22 and 23. The upper slide plate 22, which is adapted to be shifted transversely on the lower slide plate 23, see Fig. 4, is hollow and spaced from the bottom slide plate 23 by means of a Vertical wall 22a terminating in a bottom flange 22h which rests upon the slide plate 23. The plate 23 is adapted to slide longitudinally upon the table or bed 26 in ways 24. The cross slide plate 22 is adapted to be shifted transversely upon the plate 23 and is guided ln this movement by ways 25, see Figs. 1 and. 3.

Bolted to the outer face of the wall 22a of the slide plate 22 is a pressure plate or member 26. 'I'his pressure plate is of sufcient height to engage fully the upright flange of the metal strip C and has its lower edge resting upon the bottom flange 221: of the slide 22. The rear end of the pressure plate 26 is provided with a device for clamping the tail end of the metal strip C, the construction of this clamping device being particularly illustrated in Fig. 11. A block 21 is bolted at 26 to the face of the member 26 and is formed with a cavity having a Vertical wall 29 against which the flange of the metal strip ts and also having tapering top and bottom walls 3| against which a pair of wedge-shaped clamping blocks 30 engage. The clamp device also comprises an outer clamping member 32 adapted to be secured to the clamping block 21 by bolts 33. The angular faces of the wedge blocks 30 may be serrated, as shown in Fig. 11, so as to grip more eiectively the end of the strip C. After insertion of the end of the strip in the block v2'1 the bolts 33 may be tightened to force the clamping member 32 against the ends of the wedge blocks 36 and force them tightly into the cavity in the block 21 so as to iirmly grip the end of the metal strip.

In the present machine the pressure plate 26 is constructed so as to shape the metal strip C by bending the flange of the strip angularly with respect to the web, as shown by comparing Figs. 10 and 11. Accordingly, the wall 34 of the pressure plate 26 is gradually tapered from its rear end toward the front end thereof and at the point of engagement of the two slides A and B, shown in Fig. 12, where the slide A is tangent to the slide B, the wall 34 of the pressure member 26 extends at a desired angle with respect to the perpendicular. As later described, operation of the cross slide to clamp the work piece between the two slides produces the angular bend of the Work piece as illustrated. l

The forming slide B comprises a curved slide bar or member 35 which is shaped at its face adjacent the slide A in accordance with the nal shape of the work piece. This member is cut away to receive a strip 36 which is rigidly attached to the member 35 by bolts 31. The bottom of the strip 36 is formed with a notch 38 providing a recess within which the web of the metal of the work piece fits. The strip 36 and member 35 engage the flange of the work piece as well as the web thereof, as seen in Fig. 12, so as to hold the piece firmly in position during the bending operation.

The forming member 35 terminates at its forward end in a device for clamping orgripping the leading end of the metal strip C. As illustrated in Fig. 10, this clam-ping device comprises a clamping block 39 located beyond the end yof the member 26 when the parts are positioned, as shown in Fig. 2, at the beginning of an operation. The clamping block 39 is recessed to provide an inclined wall engageable with the ilange of the work piece. Mounted in a notched portion ofthe member 35 is a block 40. The member 35 together with the block 49 is adapted to be secured tothe clamp block 39 by bolts 4|. The members 49 and 35 are provided with complementary recesses 42 and 43 which together form a cavity adapted to receive a `pair of wedge blocks '44 engageable with the inclined Walls of the cavity. Upon tightening the lbolts 4| it will 4be understood that the `end of the metal strip C will be clamped between the clamping block 3'9 and the Wedge blocks 44, kthe latter preferably having serrated surfaces so as to effectively grip the surfaces of the metal strip. A cap or end'plat'e 45 bolted at 46 to the members 40 and 35, see Fig. 2, may be provided for the purpose of holding the wedge blocks v414 in proper position with respect to 'the other parts of the clamp assembly.

The forming slide comprising the members 35 and 3'6 maybe driven through the medium of a suitable sprocket and chain mechanism. In 'the present instance, as illustrated in Figs. 4 and 12, this drive comprises upper and lower sprocket chains'dland of any conventional type secured to the inner face of the forming meinbe;` 35 by means of pins 59. The chains 647 and 48 are driven by 'upper and lower sprocket wheels 59 and 50a, the upper sprocket 'having teeth 5| meshing with the chain 4'! and the lower sprocket having teeth 52 `meshing with the chain 48. The intermediate A'hub portions of the sprockets 50 and 50a, are recessed to receive a thrust bearing ring 53 which at one side engages a portion of a bracket 55 bolted to the bed 2i! and at the other side engages a thrust portion 35a of the forming member 35. Thus, transverse pressure exerted by the pressure 'plate 25 against the .ilange of the work piece and'thence transmitted to the vforming member 35 is in turn transmitted Vto the fixed bracket 55 secured rigidly to the hed '29 of the machine. The bracket 55 is in the form of a housing having an upper ,portion overlying the sprockets 'and providing a 'bearing for the upper sprocket. This bracket has a hole to receive the upper end of a shaft 54 to which the sprockets 5D and Ella are keyed.

The slide plate 23 is adapted to be shifted in a straight line path, bein"j guided in its reciprocating movement by the ways 24. This is accomplished in the present instance by .a suitable rack and gear mechanism. Bolted to the underside ofthe slide plate 23 is a rack 55 and meshing with the teeth of this rack is a gear l secured to .-a Vertical'shaft 58 extending through the bed 20 of the machine. The rack 56 and gear v5l Vare suitably housed within a recess in the bed, as illustrated in Fig. 4. Thus rotation of the `gear 5.1 in either direction will drive vthe rack '56 forwardly or rearwardly, thus imparting va rectilinear forward or rearward movement to the slide plate 23 and hence to the upper cross slide plate 22 which carries the pressure member 26 and the rear clamping device for the work piece.

Mounted upon the slide plate 22 is a -control box 59 upon which ismounted a suitable hydrauli'cpur'np 69. Fluid is discharged by .the `pump under ,pressure through ra pipe El. `A Apipe 6.2, leads y"from the pipe tl to a distributing pipe 63 extending along the rear side of the slide 22. Leading from the distributing pipe 83 at spaced intervals along the length of the slide 22 vare pipes 64, each of which is connected and communicates with a hydraulic cylinder 65 housed beneath the slide 22 and supported upon the bottom slide plate 23, see Fig. 4. Reciprocable within each cylinder 65 is a piston 66 connected to a piston rod or plunger 61 which in turn is secured at its outer end at 69 -to the wall 22a of the slide plate 22. Also communicating with the pipe 6i leading from the hydraulic pump is a pipe 69 which opens into a distributing pipe 'l5 parallel to the pipe 63 and in like manner communicating with a series of pipes l'l leading to the cylinders 65. The pipes l'l, however, communicate with the cylinders 65 at the sides of the pistons 6B opposite to the pipes 64. Thus, when fluid under pressure is introduced into pipes 62, 63 and Si the pistons 66 will be shifted forwardly thereby shifting the slide plate 22 toward the forming member 35, as illustrated in Fig. 4. The slide plate 22 may be reciprocated or shifted away from the forming member by introducing the fluid under pressure through the piping y69, l@ 'and H, thus shifting the pistons 66 in the opposite direction within the cylinders 55.

The shaft 54, which drives the sprocket and chain mechanism 59, 59a, 41 and is in turn driven from a speed reducing mechanism generu ally indicated at "12. AIn like manner, the shaft 58, which shifts the slide plates 22 and 23 longitudinally through the medium of the rack and gear mechanism 56 land '51, is driven ironia suitable reducing mechanism 'l3. The speed reducing mechanism l2 and 'I3 may be of any suitable type and, therefore, no detailed description there of is deemed necessary herein. The speed reducingmechanisms l2 and 13 'receive their power from a lsuitable variable speed mechanism indicated in general by lthe `reference numeral l5. The drive from the variable speed mechanism 16 to the `speed `reducing units 4*l2 and 'i3 is accom plished respectively through chain `drives 'ill and T5, see Fig. 5. The variable speed mechanism by which `shaft 54 may be rotated at a different speed than shaft 58 and whereby the differential speeds of these shafts may be changed or varied at will, may be of 'anycommercial or conventional type. In the present Ainstance the vvariable speed unit 16 is of the Link-Belt P. I. V. type, well known in the art. This unit comprises a selfpitching chain 11, the teeth of which engage mating radially grooved conical wheels I8 and 'i9 located on and secured to shafts 8o and 8i. Change in speed is effected by moving suitable horizontal levers inwardly `and outwardly by mam ually or mechanically turning a control screw (not shown). This brings one pair of wheels together, causing chain engagement farther from the shaft, and spreads the other pair of wheels apart, causing chain engagement closer to the shaft. The speed of the output shaft governed by the ratio of the effective diameters of the two'pairs of wheels 18 and 19, asis well known in the art. By the use of this mechanism a considerable variety of speeds may be obtained, namely, the relative speedsof the shafts 8E and 8l maybe considerably varied. Since the chain 'l5 is driven from 4the shaft `89 vand the .chain .7d is driven from the shaft 8l, it will be seen that the reduction gear .units 12 .and 'I3 may be driven from .the variable speed `unit 16 at different speeds, hence Lproducing a differential speed Vof speed unit is powered from an electric motor 82, see Fig. 1.

In operation it will be understood that the straight strip C is first clamped in position at opposite ends in the clamping devices above described and illustrated in Figs. 10 and l1. To facilitate determination of the proper relative position of the slides at the Starting point a gauge piece 83 may be fastened as by means of screws to the member 26. This gauge has a tooth 83a adapted to t into a notch in the member 36, the tooth and notch being positioned so as to mesh at the starting position of the slides. After the piece has been clamped at opposite ends fluid under pressure is introduced through pipes 54 into the hydraulic cylinders 65, four being illustrated in the present instance, thus shifting the pistons S6 and hence the cross slide plate 22 and cilitate determination of the proper relative pocausing the work piece C to be clamped tightly under pressure between the pressure member 26 and forming member 35, 36. In View of the inclined walls of these members the flange of the Strip or work piece C will be correspondingly shaped and this inclined shape will be imparted to the flange progressively as the strip is fed forwardly by the slides and progressively wrapped on the forming slide. Since the rate of speed of the latter is a calculated amount greater than the rate o1 rectilinear travel of the slide plates 22, 23 the web of the strip C as well as the flange thereof will not only be bent in accordance with the curve ci the forming slide but will be stretched as illus trated in Fig. 8, thus eliminating all wrinkles and producing a smoothly bent piece free from any compressive strains in the metal fibers.

I claim:

1. In a bending machine, a curved forming slide, a second slide arranged tangentially with respect to the forming slide, means for releasably attaching longitudinally spaced portions of a metal strip to said slides, means for relatively moving said slides to clamp the strip therebetween at their tangential point of engagement, means for shifting said forming slide in a curved path, and means for shifting the second slide in a straight line path.

2. In a bending machine, a curved forming slide, a Isecond slide arranged tangentially with respect to the forming slide, means for releasably attaching longitudinally spaced portions of a metal strip to said slides, means for relatively moving said slides to clamp the strip therebetween at their tangential point of engagement, means for shifting said forming slide in a curved path, and means for shifting the second slide in a straight line path and at a rate of speed less than that of the forming slide.

3. In a bending machine, a curved forming slide, a second slide arranged tangentially with respect to the forming slide, means for releasably attaching longitudinally spaced portions of a metal strip to said slides, means for relatively moving said Islides to clamp the strip therebetween at their tangential point of engagement, means for shifting said forming slide in a curved path, and means for shifting the second slide in a diierent path.

4. In a bending machine, a curved forming slide, a second slide arranged tangentially with respect to the forming slide, means for releasably attaching longitudinally spaced portions of a metal strip to said slides, means for relatively moving said slides to clamp the strip therebetween at their tangential point of engagement,

means for shifting said forming slide in a curved path, and means for shifting the second slide in a different path and at a lesser rate of speed than that of the forming slide.

, 5. In a bending machine, a curved forming slide,`a second slide arranged tangentially with respect to the forming slide, means for releasably attaching longitudinally spaced portions of a metal strip to said slides, means for bodily shift ing said forming slide in a curved path, means for shifting the second slide in a straight line path tangential to said curved path, and means for exerting clamping pressure on the strip at the locality of tangential engagement of the slides.

6. In a bending machine, a curved forming slide, a second slide arranged tangentially with respect to the forming slide, means for releasably attaching longitudinally spaced portions of a metal strip to said slides, means for bodily shifting said forming slide in a curved path, means for shifting the second slide in a straight line path tangential to said curved path and at a lesser rate of speed than that of the forming slide, and means for clamping the strip between the slides at their tangential point of engagement.

7. In a bending machine, a curved forming slide, a second slide, means for shifting the second slide toward and transversely to the forming slide into operative engagement therewith to clamp a metal strip therebetween, means for shifting the second slide tangentially to the forming slide, means for shifting the forming slide in a curvilinear path to bend the strip thereon, and means for varying the relative rates of travel of said slides.

8. In a bending machine, a curved forming slide, a second slide shiftable toward and trans versely to the forming slide into operative engagement with the latter to clamp a metal strip therebetween, means for shifting the second slide tangentially to the forming slide, and means for shifting the forming slide in a curvilinear path and at a greater rate of speed than that of the second slide to bend the strip thereon and also stretch the strip.

9. In a bending machine, a forming slide,

means for shifting it in a curvilinear path, a second slide, means for shifting the second slide in a path tangential to the said curvilinear path, a third slide mounted on the second slide and shiftable therewith, means for shifting the third slide transversely to the second slide to grip a metal strip between the forming slide and second slide, and means for releasably attaching opposite ends of the strip to the forming slide and to one of the other two slides.

10.1n a bending machine, a forming slide, means for shifting it in a curvilinear path, a second slide, means for shifting the second slide in a path tangential to the said curvilinear path and at a different rate of speed than that of the forming slide, a third slide mounted on the second slide and shiftable therewith, means for shifting the third slide transversely to the second slide to grip a metal strip between the forming slide and second slide, and means for releasably attaching opposite ends of the strip to the forming slide and to one of the other two slides.

11. In a bending machine, a curvilinear forming slide terminating in ends separated one from the other, a second slide, means for clamping one end of a work piece or strip to the forward end of the forming slide, means for clamping another portion of the work piece to the second slide, means for shifting the second slide generally tangentially with respect to the forming slide, means for shifting the forming slide endwise, both of said clamping means moving bodily with the slides during the shifting of the slides.

12. In a bending machine, a 4pair of devices attachable to a metal strip at longitudinally spaced points on the strip, mechanism for simultaneously shifting said devices in angularly related paths and one at a diierent rate of speed from the other, a forming member associated with each of said devices and shiftable therewith, and means for relatively shifting said forming members to clamp the strip therebetween and to maintain the forming members in operative engagement with the strip intermediate the points of attachment of said devices to the strip during travel of the strip between the forming members during the forming operation.

13. In a bending machine, a pair of forming devices having means for attachment to a metal strip at longitudinally spaced points on the strip, mechanism for simultaneously shifting said devices in angularly related paths and one at a diierent rate of speed from the other, and means for maintaining one of said forming devices in position to exert pressure against the other forming device to clamp the strip therebetween during the travel of the strip in the forming operation.

14. In a bending machine, a pair of forming devices having means for attachment to a metal strip at longitudinally spaced points on the strip, mechanism for simultaneously shifting one device in a rectilinear path and the other device in a curvilinear path and one at a diierent rate of speed from the other, and means for shifting one of said forming devices into operative engagement with the other forming device to clamp the strip intermediate the points of attachment of said devices to the strip during travel of the strip in the forming operation.

15. In a bending machine, a pair of forming devices having means for attachment to a metal strip at longitudinally spaced points on the strip, mechanism for simultaneously shifting one device in a rectilinear path and the other device in a curvilinear path at a greater rate of speed than the other, and means for shifting one of said forming devices into operative engagement with the other forming device to clamp the strip intermediate the points of attachment of said devices to the strip during travel of the strip in the forming operation.

16. In a bending machine, a pair of forming devices having means for attachment to a metal strip at longitudinally spaced points on the strip, mechanism for shifting one device in a rectilinear path and the other device in a curvilinear path, means for varying the rate of travel of one device with respect to the other, and means for maintaining one device in operative engagement with the other device to clamp the strip between the devices at the point of operative engagement thereof.

17. In a bending machine, a pair of forming devices having means for attachment to a metal strip at longitudinally spaced points on the strip, mechanism for simultaneously shifting one device -and its attaching means in a rectilinear path and the other device and its attaching means in a curvilinear path, and means for maintaining one device in operative engagement with the other device to clamp the strip between the devices at the point of operative engagement thereof.

18. In a bending machine, a pair of forming devices, means for releasably attaching longi tudinally spaced portions of a metal strip to said devices, means for operatively engaging said devices to clamp the strip therebetween at the locality of their engagement, and means for simultaneously shifting said devices in angularh7 related paths while maintaining said forming devices in clamping relation to the strip at said locality.

19. In a bending machine, a curved forming member, a slide, means for releasably attaching longitudinally spaced portions of a strip to said slide and member, means for relatively shifting the slide and member transversely into operative engagement to clamp the strip therebetween, means for shifting the slide longitudinally and tangentially to the forming member, and means for shifting the forming member in a curvilinear path to bend the strip thereon.

FRANK K. KIRSCH. 

